


One & Only

by UntilYou_FindMe



Category: Haikyuu!!
Genre: Established Oikawa Tooru/Sugawara Koushi, Fluff, M/M, Oikawa Tooru is competitive, Oikawa's sister is really sweet, Suga's brother is a mood
Language: English
Status: Completed
Published: 2021-03-15
Updated: 2021-03-15
Packaged: 2021-03-24 04:14:30
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,559
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30066504
Author URL: https://archiveofourown.org/users/UntilYou_FindMe/pseuds/UntilYou_FindMe
Summary: “Kou-chan, Kou-chan!”Oikawa started calling obnoxiously his boyfriend of 4 years, Sugawara Koushi, in order to get his attention.“What, Tooru? Why are you yelling like that?”Koushi looked at him curiously, as his boyfriend rarely sounded this stressed and impatient. Especially not without an apparent reason.“I need to tell you something! My sister is coming into town this weekend, and she demanded to spend time with you!”
Relationships: Oikawa Tooru/Sugawara Koushi
Comments: 8
Kudos: 42





	One & Only

**Author's Note:**

> Hi, Brownie here!  
> A little info to understand better. The names of Oikawa's sister and Suga's brother actually have meanings!  
> Sugawara - Sedge Plains  
> Satoshi - Clear thinking
> 
> Oikawa - Reaching the river  
> Fumiko - Child of treasured beauty
> 
> Hope this clears it a bit!  
> Now, let's start!

“Kou-chan, Kou-chan!”

Oikawa started calling obnoxiously his boyfriend of 4 years, Sugawara Koushi, in order to get his attention.

“What, Tooru? Why are you yelling like that?”

Koushi looked at him curiously, as his boyfriend rarely sounded this stressed and impatient. Especially not without an apparent reason. 

“I need to tell you something! My sister is coming into town this weekend, and she demanded to spend time with you!”

“What? Why? I’ve never met her! Is she coming here to judge me?” 

Oikawa loved Suga deeply, but he knew well how anxious he could get, and was quick to cut his spiraling thoughts down.

“Koushi, don’t worry. I’m sure it’s just one of her stunts to embarass me, and make me look like an idiot.”

Suga looked much more relieved after hearing this. 

“AND this is why I think I should also meet your little brother!” Oikawa finished with a smug look on his face.

Suga was confused. “My brother?”

“Yes Kou, your brother! I’ve never met him and I only know he’s just a bit younger than you! It’s not fair, so I want to meet him!” 

“I don’t think that’s a great idea, but if that’s what you want…” 

* * *

Satoshi Sugawara, 18 years old and this close to losing his mind at the moment, was not amused when he got told by his older brother that his boyfriend was interested in meeting and spending some time with him.

He didn’t hate the idea of his brother’s boyfriend. Not at all. He and Koushi were 6 years apart, but that never stopped them from being close to each other, so he was genuinely happy for his older brother. 

What he **really** didn’t wanna have to deal with was the boyfriend himself. He had heard thousands of stories from when his brother was in high school and had some kind of rivalry with this guy, and that really didn’t put him under a favorable light in his eyes.

[This may also have been Daichi’s fault, since he was the most vocal about his distaste for the Seijou captain back in high school and left a deep impression on poor little 12 year old Satoshi]

It didn’t get better when Oikawa texted him to let him know that he would be picking him up from school after his Saturday morning practice was done. He already didn’t want to have to deal with him, much less right after a tiring practice. 

Sighing, Satoshi picked up his bag and walked outside, where he got greeted by an embarrassingly loud “Yahoo~ Satoshi-chan!” which only made him want to hide so he wouldn’t be seen by his club’s juniors.

This already was beginning to look like a LONG day.

* * *

Despite being extremely anxious about how his meeting with Oikawa’s sister would go, Suga was overly relieved to find out that Fumiko Oikawa was actually a really sweet person. She was maybe a little pushy, but that was simply an innate quality of the Oikawa family.

“Hi! I’m Fumiko. My idiot brother must have told you about me.” Fumiko introduced herself to Suga with a sweet smile.

“Oh, yes Oikawa-san…” Suga tried to say. 

“OH NO YOU DON’T” Fumiko hastily interrupted him. “You aren’t gonna use that formal tone with me. You’re literally my saint, my saviour that decided to put up with my little brother! Now, let’s not waste time and go get a drink together!”

Suga could finally breathe and smile. His nervousness finally releasing him from its grasp and cheerfully replying “Yeah, let’s go!”

“You’re so cute when you smile, really! You are too good for my brother... What are we gonna do?” Fumiko joked, or at least Suga hoped so, and led him towards the cafè where she wanted to go.

* * *

Oikawa would say that he was quite good with kids, even if his last bit of proof was his nephew he used to watch when he was 18 years old.

The kid that stood in front of him was almost as tall as Oikawa himself.

Definitely not the “cute and sweet little angel” Koushi had described. In his defense, Koushi made him sound like he was 12 years old, not 18 for crying out loud!

He called out to him, hoping to sound as carefree and friendly as possible (was that a frown on his face? Why would he be making a face like that? Oikawa really couldn’t understand).

Looking back, Oikawa realized he might have come off as… presumptuous, to put it nicely.

“Hey Satoshi-chan! Can I call you like that?”

He started bombarding the kid with questions, true to the Oikawa family’s style.

“I’ve planned the whole day to hang out. I’m a busy person, but I made time just for you!”

Satoshi looked straight at him with a gaze and a calm demeanor that honestly scared Oikawa.  _ He really lives up to the meaning of his name, he’s really a kid that thinks clearly  _ the setter thought. 

“I’m sorry” the teenager started. “I’m not sure what Koushi told you, but I’m not interested in wasting my day wandering around with you,  _ Oikawa-san.”  _

Oikawa felt his jaw drop. 

The younger of the two continued “I hope you have a real plan and reasons to be using my time like this. I’m busy too” he started walking forward for a bit before turning back, smirking. “and Koushi would hate it if you made me waste my time.”

Oikawa was sure he heard something inside him snap. He didn’t want to believe his own ears. This kid, this absolutely rude child, was giving him sass? After he so graciously set time aside to get to know him and even implied Koushi would be upset with him for this? Oikawa decided then and there that he would absolutely not lose against the youngest Sugawara.

[He later admitted that going against a 18 years old kid was NOT one of his smartest moves, but at the time it looked like the only rational thing to do, sue him]

* * *

Was Satoshi going down the antagonistic route? Yes. Did Oikawa really deserve that? Rationally no, but in his teenager mind he totally did. Was he going to regret it? Not really, unless Koushi catches wind of this.

He may act tough and cool, but he will never admit to others that he’s actually really scared of what an angry Koushi could do, and he looks up to him too much to disappoint him.

Even if he really didn’t want to, he resigned himself to following Oikawa to wherever he wanted to go for their get together. Apparently his plan was to win him over in some way, starting by buying him food. 

“Come on, Satoshi-chan, let’s go eat first, you must be starving.”

Satoshi noticed a change in the tone of the older.  _ It didn’t take long to mess with him, huh?  _ he smugly thought.  _ Well, that just proves my point then. _

After eating, Satoshi had to begrudgingly admit that Oikawa looked like he was putting some effort into all of this. Taking him to eat in a good place, trying to talk a bit with him and actually acting like a normal human being. 

[The old warning given to him by Daichi, “Never trust someone like Oikawa, Satoshi! Types like him are sneakier than what you could ever think of!” made him act a little more wary of the setter in front of him. Poor Daichi didn’t know that while he was saying this to the younger Sugawara, the older one was talking with the man in question.]

He still didn’t feel completely at ease with Oikawa. Satoshi could see that the man was trying his best to show interest for the younger, and he was really starting to feel bad about how he acted towards him before. He decided to put a little more effort into his replies, letting Oikawa know a little about his school life, how he and Koushi spend their time when they are together and even talking about his role as a regular and Vice-Captain in Karasuno’s volleyball club.

This bit of information really seemed to spark something deep inside Oikawa. Satoshi could see that the man in front of him had regained some confidence and attitude when he told him that specifically he played as a wing spiker for his high school’s team. 

“Say, Satoshi-chan” Oikawa started after they left the restaurant. “care to play a little with me? Come on, amuse me for a little.”

While Satoshi was still evaluating the pros and the cons of this offer, Oikawa turned around, facing him.

“You know, I’m a very good setter… One that even your  _ beloved _ older brother looked up to.”

Satoshi was no longer feeling guilty about wanting to smash Oikawa’s face with a serve.

* * *

Oikawa was not proud of the way things were going, but he really hoped to turn things around after showing this brat how amazing and deserving-of-respect he is.

His only consolation was that he was sure that Koushi also must have been having a hard time with his sister. Fumiko Oikawa was really a force to be reckoned with.

[At that exact moment, Koushi was happily sharing a slice of cake and a cold drink with Fumiko while talking about the younger Oikawa’s embarrassing stories from childhood. All in all, he was having a blast]

Oikawa led Satoshi to a park where he used to train when he was younger, which was conveniently equipped with a little volleyball court. 

“Come on, show me what you can do.” the setter made the first move this time, not giving the younger time to protest. 

Oikawa knew that Satoshi would never step down from a challenge, and the older knew that riling up his opponents was one of the things he did best, on and off the court. The setter headed towards the end of the court without hesitation, preparing himself to serve. 

The youngest Sugawara took his place on the opposite side of the court, ready to receive the infamous jump serve of the setter. Despite it being years since Oikawa had left the high school’s volleyball scene, his accomplishments were still remembered among high schools’ volleyball clubs and an object of admiration for the players. 

All of this was enough to put pressure on the average high schooler, but stubbornness and the confidence in his own skill didn’t let Satoshi falter in front of Oikawa. He had always trained hard in order not to let his brother down. Not to mention that he needed to live up to the reputation that Karasuno got for their stable and solid receiving in order to keep his place as a regular, all thanks to Daichi’s captaincy years prior.

“Bring it on!” was all Satoshi could say before getting hit by what looked more like a rocket rather than a volleyball. He barely received it, getting it almost to the standard setter position under the net.

“Not bad, Satoshi-chan! Not bad at all… Now, let’s see how far you can actually go.” 

* * *

Suga was really enjoying his meeting with Fumiko Oikawa. 

She was a really witty, clever and interesting person. One that no one could take their eyes off of for long. It must be an Oikawa family’s special talent, as Suga could really see the similarities between the two charming siblings. 

After a couple of hours spent talking, joking and getting to know each other, they finally made their way out of the cafè.  _ Time really flew by… _ Suga thought, looking at the setting sun.

“Hey Koushi-kun… Can I ask you something?” 

Suga was honestly startled by the quiet tone Fumiko was using. He had only heard her using a confident and almost too loud voice when talking, so this was entirely new to him.

“Yes, Fumiko-san?”

“Do you love Tooru?”

“Sorry?”

“Do you love my brother? He may be an idiot, but he’s really a good kid and deserves all the love and attention in the world. So, do you love him?”

Suga stopped walking and looked at the woman in the eyes. The orange hues from the sunset were coloring everything near them, making Suga suddenly realize that this moment was the real goal of this whole set up. It took the air away from his lungs for a moment, feeling overwhelmed. He felt his face get red and before losing courage he replied to her.

“Fumiko-san. I will never love someone as much as I love Tooru. You can rest assured.” 

The woman smiled, quickly replacing her earlier solemn expression with a much more relaxed one.

“I’m so glad, really.”

* * *

After a good deal of hitting back and forth the ball, of setting and spiking together and overall exhausting themselves, Satoshi had to admit that Oikawa was really the best setter he had the privilege of working with.

Lying on the floor, Satoshi sat up and looked over at Oikawa, who was just as out of breath as he was, but was trying to hide it. 

“So… Oikawa-san. I’m still not sure what you wanted to gain from hanging out with me, but I understand why you’re so respected by people.” 

Oikawa raised an eyebrow, prompting the teen to keep going.

“I didn’t really like the idea of you going out with my brother. Your fame has always preceded you, and I was really worried. Koushi is really my idol in a way. He’s always been there for me as a kid, and I really care about him. That’s why now I have a question for you.”

Satoshi paused, thinking of the weight and the importance that the words he was about to say carried with them.

“Do you love my brother, Oikawa-san? Be honest with me.”

Oikawa looked stunned for a second before a serious expression came over on his face, his features darkening with determination and looking at the boy firmly.

“Yes, I love him with all of my heart. Nothing will ever make me turn away from him. He’s the one I want and I will fight for him. I’m not new to struggling to get what I want, and I want to stay by his side.”

Satoshi looked at him for a moment before bursting into laughter. Oikawa was bewildered, but he kept howling. Once he calmed down, he looked at the older and smiled.

“I’m relieved to hear that. I was wrong, you’re exactly what Koushi needs and deserves. Keep it up Oikawa-san, I kinda like you now.”

Oikawa helped Satoshi up, and before he could even open his mouth, the kid gave him something like a glare, making Oikawa freeze in confusion.

“But just so you know, if Koushi gets hurt, I will personally find a way to make you regret every single day of your life. Don’t underestimate me, and remember that I’m not as forgiving as Koushi is.” 

Satoshi then flashed him a brilliant smile, reminding Oikawa of Koushi’s own. Maybe just a little more devious compared to the older Sugawara.

_ They really look alike. It’s just their personalities that are like day and night _ .

While Oikawa was lost in this thought, the teen had already started to walk away, leaving him behind.

“You are really a little devil!” Oikawa shouted, half annoyed but mostly smiling fondly at the back of the younger Sugawara.

  
  


**Author's Note:**

> Thank you for reading!  
> A really big thank you to melons that helped correcting my subpar english grammar and mori for also beta-reading for me!  
> I love you so much♥
> 
> Let me know what you think in the comments!


End file.
